Certain subterranean formations may include organic matter, such as shale oil, bitumen, and/or kerogen, which have material and chemical properties that may complicate production of fluid hydrocarbons from the subterranean formation. For example, the organic matter may not flow at a rate sufficient for production. Moreover, the organic matter may not include sufficient quantities of desired chemical compositions (typically smaller hydrocarbons). Hence, recovery of useful hydrocarbons from such subterranean formations may be uneconomical or impractical.
Generally, organic matter is subject to decompose upon exposure to heat over a period of time, via a process called pyrolysis. Upon pyrolysis, organic matter, such as kerogen, may decompose chemically to produce hydrocarbon oil, hydrocarbon gas, and carbonaceous residue (the residue may be referred to generally as coke). Coke formed by pyrolysis typically has a richer carbon content than the source organic matter from which it was formed. Small amounts of water also may be generated via the pyrolysis reaction. The oil, gas, and water fluids may become mobile within the rock or other subterranean matrix, while the residue coke remains essentially immobile.
One method of heating and causing pyrolysis includes using electrically resistive heaters, such as wellbore heaters, placed within the subterranean formation. However, electrically resistive heaters have a limited heating range. Though heating may occur by radiation and/or conduction to heat materials far from the well, to do so, a heater typically will heat the region near the well to very high temperatures for very long times. In essence, conventional methods for heating regions of a subterranean formation far from a well may involve overheating the nearby material in an attempt to heat the distant material. Such uneven application of heat may result in suboptimal production from the subterranean formation. Additionally, using wellbore heaters in a dense array to mitigate the limited heating distance may be cumbersome and expensive. Thus, there exists a need for more economical and efficient heating of subterranean organic matter to pyrolyze the organic matter.